Preparation of filamentary material



Patented Aug. 5, 1952 PREPARATION OF FILAMENTARFY MATERIAL Culpepper,Newark,N.J;, andlLesterW. Latt'a, Lynb'mok, N. Y., assigno'rs to Celanese. 1 Corporation of America,,New York, N, Y,, a v

. ,c m ii no fl a j Application'october 5,1949; Serial No. 119.614

f ;f1o Claims. (01.18 8) i l. This invention relates to the preparation of filamentary material and relates more particularly to the preparation of filamentary material by the band spinning process. Y a In the preparation of filamentary material such as yarns, filaments, ribbon and the like by the band spinning process,-a bandof filamentforming'material is entered at a constant rate, by" means such as feed rollers, intoaheate'd melting tube having: a passageway extending therethrough of such size and shape as approximately to fit the band, which passageway leads to a spinning jet containing at? least one. spinning orifice- The filament-forming material melts and. is brought. to theproper temperature for spinning as it traverses the melting tube. to the spinning. jet. and the molten: filament-forming material is forced through thespinn'ing orifice by the pressure developed bylthe. incoming band, which. :acts as a continually-renewed Lpiston. Among the filament-forming materials that may be spun in this manner are, for. example, the polycarboxamicles, polysulfonamides, v..p.olyure-' thanes,.polytriazoles and the like.

.We have found that. in producing filamentary material by the. band spinning-process, there is a tendency for the" band to-jam in'the feed mechanism or in the passageway, which jamming is highly objectionable since. it interrupts the continuity of spinning. .Moreover, when spinning is interrupted, the molten filament-forming material remaining in the: :melting; tube-;tends to decompose or degrade so' that the melting tube must be. disassembled and cleaned before spinning' can- ,be-resume'd; "In additiom. .we have found that during spinning the filament-forming material tends to'decompose at 6.1511011? distance. say 1;oi' 1.l' -;inches from the entrance to, the passageway, and thatthe decomposition products which are formed tend to accumulate in and obstruct said passageway, requiring frequent interruptions to spinning for; their removal.

Itis animportant objectof this invention to provide a process and apparatus for preparin in which spinning may be carried on forextendedperiods of time without interruption.

Otherobjects of our invention, together with certain details of construction and combinations,

of parts, will be apparent from they following detailed I description and claims.

We have now discovered that the. jamming of the-band of filament-forming material in the feed mechanism results from a softening of the portion of theband between the feed rollers and the entrance to the meltingtube. produced by the heat reaching said band. from the melting tube. If a considerable amount ofgsoftening. takes place, jamming will occur with ascomplete interruption in spinning. On the other hand, if only a limited amount of softening takes place, spinning may continue, but the band will be deformed, causing a variation in the rate at which the fi1ament-forming matefial enters the melting tube, which in turn will produce an objectionable variation' in the" denier of the filamentary material being produced.

To eliminate the jamming or deformation of the portion; of the hand of filament-forming material between the feed rollers and the entrance; to the melting tube. we provide a cooling means to prevent a-sottening of said band until after it has entered said melting tube. The cooling means may, for example, take the form of a collar encircling the band and positioned between the. melting tube and the feed rollers, through which collar a cooling medium such as water is circulated to. carry away the heat emanating from the melting tube. y 7 i While the'provision of a cooling means to preventan increase in the temperature and a softening of the band of filament-forming material untilafter it hasv entered the melting tube eliminates the jamming or deformation of the band in the feed rollers, it has no efiect on the tendn 0 th and to iamzinthe passa eway. W have discovered that the-jamming of the band in the passageway results from the manner. in which the band melts as it traverses said passageway. When the band enters the passa eway and contacts the walls thereof, its outer surfaces begin to melt while its core remains solid. Then as the band-passes farther into the passageway moreof the filament-forming material on its outer "surfaces melts andits'core becomes plastic. The completemelting -of the band takes place slowly when the same amount of heat is supplied to the band for the'entire length of the passageway. As a result, the length of the plastic, but still unrnelted, core of the band-becomes so reat thata very small obstruction to the movement of. its tip-is enough to halt the movement of the band and causethe band to jam progressively tighter andtighter in h passageway. When out interruption.

3 a jam of this type takes place, it is not possible to move the band with thrusts of up to 300 pounds, although a thrust of only a few pounds is sufficient for spinning under normal conditions. We have discovered that the jamming of the band of filament-forming material in th passageway may be eliminated by supplying a greater amount of heat to that portion of the passageway into which the band first enters than .10. band will be melted rapidly and the moltenfilato the remainder of said passageway, so that the ment-forming material will be brought to the proper temperature for spinning. This may; be. effected by positioning a number of heating elements along the length of the melting tube and raising the heating elements adjacent that porw a. r

" equal to the cross-section of the band. As

tion of the passageway into which the band first I enters to a higher temperature than the re mainder of the heating elements. Alternatively,

or in addition, the walls forming that portion of the passageway into which the band first .enters may be made of higher thermal conductivity than the walls forming the remainder of the passageway. For example, the walls forming that portion of the passageway into .Which'the band first enters may be of a different material and/ or thinner in cross-section, while the walls forming the remainder of the passageway may be provided with a layer of insulating material. In general, it is desirable to melt the band of filament-forming material as rapidly as possible without employing temperature so high as to cause an appreciable decomposition of the filament-forming material.

During the spinning, the filament-forming material tends to decompose-'ata short distance from the entrance to the passageway althoughit remains at this point for only a very short interval of time. The products formed during the decomposition of the filament forming material accumulate in and obstruct'the passageway, requiring frequent interruptions to spinning for their removal. Wehave discovered that the decomposition of thefilament-forming material may be eliminated or minimized by passing a stream of a gas, such as nitrogen, which'is chemically inert to the filament-forming material, over the entrance to th passageway to exclude atmospheric oxygen from contact withthe heated band or the molten filament-formingmaterial. By using this expedient, it is possible to carry on spinning for extended periods of time with- A preferred embodiment of our invention will now be described with particular reference to the accompanying drawing in which Fig. 1 is an elevational view,- partly in section, of the band spinning apparatus, and

Fig. 2 is a cross-sectional View, taken on the line 22 in Fig. l in the direction of the arrows.

Referring now to the drawing, the reference numeral ll designates a guide member into which a band of filament-forming materialinot shown) is entered. The guide member leads the band of filament-forming material between feed wheels I2 and [3, at least'one of which is positively driven by any suitable means (not shown), which grip the band and feed the same forward at a constant rate. To prevent slippage of the band between the feed wheels l2 and [3, the surface of one or both of said feedwheels may be serrated or otherwise roughened and the feed wheels may be spring-pressed against each other in a manner well understood in the art.

After passing between the feed wheels l2 and shown, the collar 16 is spaced from the guide member I4 and the melting tube [8. It is to be "understood, however, that the collar [6 may be .fabutted against one or the other of said members. The meltingtube I8 is provided with a number of heating elements, such as electric heating coils 2| which are positioned along the length of said :meltingtube and which may be individually controlled. There are provided also a series of thermocouples 22 to measure the temperature of the melting tube I8 along the length of the passageway 19. The signals from the thermocouples 22 may be employed to control automatically the magnitude of the current .fiowing to each of the several electric heating coils 21 so that the temperatures along the passageway!!! will remain constant at alltimes.

Adjacent the entranceto the passageway [9, there are provided a pair of opposed channels 23, which extend through the body of the melting tube l8 and intersect the passageway [9. A stream of a gas, suchas nitrogen, which is inert to the filament-forming material, is entered into the channels 23 from any, suitable source (not shown) through conduits 24. The incoming nitrogen flows to the atmosphere through the passageway [9 between the surfaces of'the entering band and the walls of the melting tube l8, effectively excluding. atmospheric oxygen from contactv with the heated'band'or molten filamentforming materiaL; andthereby eliminating'or minimizing the decomposition of the filamentforming material.

From the passageway [9, the molten filamentforming material enters a well 25 in which a thermocouple 26 is positioned to measure the temperature of the filament-forming material immediately before it is sp'un; The molten filament-forming material then passes through a stainlesssteel filter screen Zlto remove any particles of foreign matter therefrom, following which the molten filament-forming material fiows through the orifices (not shown) in the spinning jet 28. 'If desired, a sand filter may be placed above the stainless steel filter screen 2 further to filterthefilament-forming material, in a manner well understood in the art. The outer or exposed surface of the spinning-jet 28 may be given a high polish, which serves to reduce the heat radiated to the filamentary material from the surfaces of said jet and also to conserve the heat in the mass of molten filament-forming material contained within the'well '25. The outer or exposed surface of the spinning jet 28 may be coated with a layer or filmfo'f silicone grease or graphite to make the jet: self-starting when spinning is begun and also remain the removal of any deposits that accumulate'on the surface of said jet during Ss'pinning. -'The filter screen 21 and the spinning jet 28 areheld securely in position by means of aretaining-ring 29, which is aeoasoa cumulate .on the outer surface of said spinning jet.. To .prevent'or minimize the decomposition of the filament-forming material, there may be provided a;,ring 3 supported'on straps 32 and having a series of, inwardly directed apertures 33 therein to which a streamof a gas, such as nitrogen, which is inert to the filament-forming material, is supplied from, asuitable source (not shown) through a conduit 3.4. The stream of nitrogen blankets the outer surface of, the spinning jet 28 and'serves to prevent or minimize the decomposition of, thefilament-forming material. After cooling, the filamentary material may be passed through a humidifying chamber to increase its'moisture jcontent, lubricated and wound in package form, all as well understood.

in the art. i

The following example isgiven to illustrate this invention further.

Example The upper part of themelting tube 18 of the apparatus shown in the accompanying drawing is brought to a temperature of 290 C. and the lower part of said melting tube is brought to a temperature of 275 C. The passageway 19 is flushed with nitrogen and a band of a polycarboxamide prepared bythe polymerization of hexamethylene diamine and adipic acid is entered into said passageway. Spinning starts easily and a filament yarn having a total denier of 120 is-spun at a speedof 665 meters per minute for an extended period oftime without any'lamming of the band between the feed rollers I2 and [3 or in the passageway 19 and withoutany accumulation of deposits .at the entrance to said passageway.

I While we haveshown the passageway" l9 as of rectangular cross-section, a passageway of other cross-section,such as circular or oval, for example, mayalso be employed, in which case the cross-section of the band of filament-forming material will be varied so as approximately to fit said circular or oval passageway. In addition, the cross-section of the passageway l9 need be approximately equal. to'that of the band only in the vicinity of--the entering end of the melting tube I8, and the remainder of the passageway I9 may be of different cross-section from that of the band of filament-forming material.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit I of our invention.

Having described our invention, what we desire to secureby Letters Patent is: I

1. In an apparatus for the preparation of filamentary material by the band spinning process, the combination with a melting tube having a passageway extending therethrough, of feed rollers for entering a. band of filament-forming'material into. said passageway, said feed rollers being spaced from said melting tube and a collar encircling said band and positioned in the space between said feed rollers and said melting tube and spaced from said feed rollers and said melt ing tube, said collar having a duct therein for the passage of a cooling medium to prevent a softening of said band between the feed rollers and the entrance to the melting tube.

2. In an apparatus for the preparation of filamentary material by the band spinning process, the combination with a melting tube having a passageway extending therethrough, of feed meansfor. entering a band of filament-forming material intosaid passageway, cooling means for preventing a softening of said band between the feed means and the, entrance to the melting tube, means for passing a-stream of gas which. is inert to the filament-forming: material over the en-. trance to said passageway to exclude atmospheric oxygen from contact with the heated band or molten filament-forming material, and means for supplying a greater amount of heat to that portion of the passageway into which the band first enters than to the remainder of said passageway.

3. In an apparatus for the preparation of filamentary material by the band spinning process, the combination with a melting tube having a passageway extending therethrough, of, .;-.feed rollers for entering aband, of filament-forming material intosaid passageway, a collar, encircling said band and positioned between said feed rollers and said melting tube, said collar having a duct therein, for the passage, of, a cooling medium to prevent a softening of said band between the feed rollers and the entrance to the melting tube,

terial over the surfaces of the band as it enters said passageway to exclude atmospheric oxygen from contact with the heatedband or'molten filament-forming material, and a plurality of individually controlled heating elements .positioned along the length of said melting, tube wherebya greater amount of heat maybe supplied to that portioni of the passageway into which the band-firstgenters'than to, the remain-- der of saidpassageway; 4. In an apparatus for the preparation of filamentary material by the band spinning process, the combination with a melting tube having a passageway of rectangular cross-section extending therethrough, of feed rollers for entering a rectangular band of filament-forming material having, a cross-section approximately equal to that of the passageway into, said passageway, a collar encircling said band and positioned between said feed rollers and said'melting tube, said collar having a duct therein for the passage of a cooling medium to prevent a softening. of the bandqbetween the feed rollers and the entrance to the melting tube, a pain of opposed channels extending through the body of the melting tube. and intersecting said passagewayfor the passage of a: stream of gas which is inertto the filamentf-orming material over the surfaces of the band as it enters;said passagewayto. exclude atmospheric oxygen from contactwith. the heated band or molten filament-forming material, a plurality of individually, controlled electrical heating coils positioned along the length of said melting tub-e whereby a greater amountv of heat may be sup-- plied to that portion of ,the passageway into which the band first enters than to. the remainder of said passageway, a filter screen for removing extraneous foreign particles from the molten filament forming material, and a spinning jet having at least one spinning orifice for shaping the molten filament-forming material and having a polished outer surface for reducing the heat radimaterial, passing the band into a first zone having an entering portion whose cross-section is 7 approximately equal to that of the band to melt the band, cooling the band before its'e'ntry'into said heated zone to prevent a softening of the band before-its entry into said heated zone; passing a stream of nitrogen over the entrance to said heated zone 'toexclude' atmospheric oxygen from contact with the heated band or molten filamentforming material, passing the molten filamentforming material through a second zone to bring the molten filament-forming material to the proper spinning temperature, and supplying a greater amount of heat to' said first zone than to said second zone.

6. In an apparatus for the preparation of filamentary mate'rial by the band spinning process, the combination with a melting tube having a passageway extending therethrough, of feed means," spaced from"sald me lting tube, for entering: aband of filament-forming material in said-passageway, cooling means positioned in the space between said feed means and said melting tube and spaced'from' said feed means and said melting tube for preventing a softening of said band between the 'feed means and the entrance to the melting tube, and means, including a channel extending through the body of said'melting tube and intersecting said passageway in'said melting tube, for passing a stream of gas,'which is inert to the filament-forming material, over the entranceto said passageway of said melting tube to exclude atmospheric oxygen from contact with the heated bandor molten filamentforming material. 4 'L'In an apparatus for the'preparation of filamentary-material by the band spinning process, the combination with a melting tube having a passageway extending therethrough, of feed means, spaced from said melting tube, iorentering a band'of filament-forming material in said passageway, cooling means positioned in the space between said feed means and said melting tube and spaced from said feed means and said melting tube for preventing a softening of said band between" the feed mea'nsand the entrance to the melting tube, and means, including a pair of opposed channels extending through the body of said melting tube and intersecting said passageway in said melting tube, for passing a stream of gas,zwhich is inert to the filament-forming material, over the entrance to said passageway of said melting tube to exclude atmospheric oxygen from contact with the-heated band or molten filament forming material. p

8. In an apparatus for the preparation of filamentary material by the band spinning process, the combination 'withamelting tube having a passageway extending therethrough, of feed means, spaced from said melting tube, for entering'a band of filament-forming material in said passageway, cooling means positioned in the space between said feed means and said melting tube and spaced from said feed means and said meltingtube for preventing a softening of said band between the feed means and the entrance to the melting tube, means for passing a stream of gas, which is inert to the filament-forming material, over the entrance to said passageway of said melting tube to exclude atmospheric oxygen from contact with the heated band or molten filament fo'rming material, and means for supplying a greater amount of heat to that portion of said passageway into which the band first enters than to the remainder of said passageway.

9. In an' apparatus for the preparation of filamentary material by the band spinning process, the combination with a melting tube having a passageway extending therethrough, of feed means, spaced from said melting tube, for entering a band of filament-forming material in said passageway, cooling means positioned in the space between said feed means and said melting tube and spaced from said feed means and said melting tube for preventing a softening of said band between the feed means and the entrance to the melting tube, means, including a pair of opposed channels extending through the body of said melting tube and intersecting saidpassageway in said melting tube, for passing a stream of gas, which is inert to the filament-forming material, over the entrance to said passageway of said'melting tube toexclude atmospheric oxygen from contact with the heated band or molten filament-forming material, and means for supplying a greater amount of heat to that portion of said passageway into which the band first enters than to the remainder of said passageway.

10. 'In the preparation of filamentary material bythe' band spinning process, the steps which comprise forwarding a band of filament-forming material, passing the band into a first zone to melt the band, cooling the band before its entry into said heated zone to prevent a softening of the band before its entry into said heated zone, passing a stream of nitrogen over the entrance to said heated zone to exclude atmospheric oxygen from contact'with the heated band or molten filament-forming material, passing the molten filament-forming material through a second zone to bring the molten filament-forming material to the proper spinning temperature, and supplying a greater amount of heat to said first zone than to said second zone.

FRANK M. CULPEPPER. LESTER'W. LATTA.

REFERENCES CITED V The following references are of record in the 

